


One-Man Army

by HimeBee



Series: Tumblr Commissions [23]
Category: Fate/Grand Order
Genre: Choking, Creampie, Doggy Style, F/M, Outdoor Sex, Rough Sex, Size Difference, Teasing
Language: English
Status: Completed
Published: 2020-11-15
Updated: 2020-11-15
Packaged: 2021-03-09 22:35:29
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,054
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27573896
Author URL: https://archiveofourown.org/users/HimeBee/pseuds/HimeBee
Summary: You end up spending some quality time with Cu after a Rayshifting mistake followed by battles after battles that weaken him slightly.What happens if the topic of a mana transfer is brought up..?
Relationships: Cú Chulainn Alter | Berserker/Reader
Series: Tumblr Commissions [23]
Series URL: https://archiveofourown.org/series/1573444
Comments: 2
Kudos: 118





	One-Man Army

**Author's Note:**

> ☆ This commission is for a friend on Tumblr, and I apologize for the delay! Every time I just wanna write and enjoy smut, life seems to wanna kick me in the teeth <<
> 
> ★ Anyway, I really hope you enjoy this because I love Cu Alter so much 💞 He's one of my favorite Servants ^^ 
> 
> ☆ And to whoever else reads this, I hope you enjoy it as well!

Although some would consider your current situation an absolute mess, you weren’t sure you would call it that specifically. Despite the fact that Cu Chulainn Alter was the only Servant currently at your disposal and you were running low on supplies, it wasn’t the worst scenario, given many things.

In your opinion, it was probably one of the best outcomes surrounding not-so favorable circumstances due to the Berserker’s strength. He was able to make up for your lack of functioning magical circuits, and the fact that you had no other Servants for support with raw power. Frankly, he was a one-man army.

Your situation could be worse, but you were just lucky to have Cu. Part of you also hoped that you could take this time to deepen your bond with the Berserker. After all the walking you two had done, the sun had eventually set, darkening the forest you had only just entered.

“Maybe we can rest here for the night then? What do you think, Cu?” He responded with a grunt that you assumed was in affirmation. He wasn’t much of a talker.

Fortunately, it wasn’t too dark to the point where you were unable to see anything. The moon’s light was bright enough to illuminate the small area the two of you had stumbled upon; a circle enclosed by tall trees. You could rest here for the time being, until Cu was ready to move once more.

“...I don’t sense any enemies nearby.” You watched quietly as Cu surveyed the forest quietly, still clutching his spear. He didn’t plan on resting, did he?

“Thank you, Cu.” The Berserker scoffed as he regarded you with a slight glare.

“I’m merely doing my duty as a Servant. Don’t go thanking me each and every time… It’s annoying.” You could feel your face heating up as you went to retort, only to be cut off by Cu.

“Shut up — this is how a Master and Servant should normally be.” With that being said, he turned his back to you and stalked off toward a tree, leaning his arm against it as he spoke to you over his shoulder.

“Now rest. I’ll keep watch.” Despite the fact that his tone left no room for any sort of disagreement, you still decided to voice your concerns as you took a seat on the ground.

“You don’t plan on resting too? You’ve been fighting all day and you’re running low on mana…” Considering he was watching you over his shoulder, you couldn’t quite make out his expression… But you could hear the blatant amusement in his voice.

“Sure, I am running low on mana. What is a third-rate mage like you gonna do about it?” His comment about you being third-rate was quite unnecessary and unfair, really… If he didn’t think you were any use to him, then you would prove him wrong.

“How about a mana transfer then?” You suggested with a leveled tone, which only served to amuse Cu even further as he started to chuckle.

“You must be joking. A mana transfer? Between the two of us? Heh, I highly doubt you would even be able to handle me.”

“Don’t be so sure.” With a hardened expression, you spoke without stuttering; much to your surprise.

Seeing as how you weren’t backing down, Cu turned around and started walking toward you. You had to make a conscious effort not to visibly gulp as he sat down in front of you, dematerializing his spear after tossing his cloak to the ground beside you.

With only a few feet separating the both of you, it was becoming increasingly clear that Cu was avid about calling you out on what he assumed to be a bluff.

“Well? You waiting on an invitation or what? Come on.” Your Servant patted his lap, signifying where he wanted you to be.

You knew he wouldn’t let you hear the end of it if you were to renege on your offer of a mana transfer, so you decided to cast your nervousness aside (for the moment) and straddle him. The grin on Cu’s face widened, displaying his razor-sharp teeth as you went to wrap your arms around his neck.

He said nothing as you nervously kissed his face and began slowly grinding against him. At the very least, you knew what a mana transfer entailed…

“Do you have any idea of what you’re getting yourself into, little Master?” You decided to shut him up with a kiss, to which Cu was more than happy to return — surprisingly.

“After seeing you fight… I think I have a pretty good idea, yeah.” Although you knew he didn’t plan on tearing you to bloody shreds like he did his enemies, you couldn’t help but wonder if Alter was just as ferocious with something as intimate as sex…

Even if he was, you were already in too damn deep to just stop and pretend as if nothing had transpired between the both of you. With that in mind, you continued to grind down against him with the pace of a snail whilst consciously noting how your panties were already becoming damp.

The longer you two kissed, the more his claws dug into your hips. It didn’t matter that your skirt was in the way, you could _still_ feel the sharpness of his nails through the fabric. Your mind began to wander, imaging what it would feel like to have his claws against your bare flesh.

At first, Cu seemed to be fine with allowing you to set the pace… But he wasn’t exactly the most patient man. As soon as you felt his grip on your hips tighten and he was suddenly tossing you down on top of his discarded cloak, you knew his patience had run out completely.

“On all fours, and take off your clothes.” Feeling slightly dazed from just being manhandled as if you weighed nothing, it took you a few moments to assume the position and pull your skirt down; which of course didn’t make Cu happy.

A startled yelp slipped past your parted lips in response to the sound of your tights being ripped like paper. He couldn’t be bothered to properly undress you, if his low growling was anything to go by. With your skirt and panties pulled down, and a huge hole in your tights, you were starting to get cold.

You were going to voice your complaints until Cu readjusted his grip on your hips and pulled you backwards, impaling you on his cock with one swift motion. A high-pitched cry of his name forced its way out of your mouth as you struggled to grip onto the fabric of his cloak in order to brace yourself against his brutal thrusting.

From the angle you two were currently in, he was able to reach places inside you that felt like it should be impossible. Cu grunted as he placed a hand around your neck and squeezed, anchoring you in place whilst he pounded wildly into you, causing your body to lurch forward with each thrust.

You whimpered and attempted to squirm a little bit, only for his grip to tighten slightly on your neck. You just wanted to slump or shy away, yet the hand cupped around the apex of your neck was hindering you from escaping from him. Cu chuckled into your ear as he leaned over your back, urging his cock deeper.

“Trying to run away, huh..? You changed your mind that quick?” You knew he was teasing you, but you couldn’t even form the words to retort.

Drool spilled from the corner of your lip and you could feel tears pooling in your eyes while you struggled to keep up with his roughness. You weren’t sure what you were expecting from Cu Chulainn as a Berserker — _of course_ he wasn’t going to go easy on you.

 _”A-ahh,_ Cu…” You felt as if he was going to break you in half…

It was fairly difficult to speak, let alone make complete sentences when he was fucking you so hard. Your mingled sounds of pleasure and the harsh sound of his hips hitting against your own echoed throughout the forest, sounding in your ears more than once. You would’ve been embarrassed if you took a moment to actually think, but you couldn’t…

“Endure it a bit longer. The transfer’s almost done.” Little shivers ran down your spine as he spoke directly into your ear, warm lips pressed against the shell.

The sensation had completely devoured as you reached your peak and clamped down on Cu’s monstrous cock, causing your juices to spill out past where the two of you were joined. You couldn’t tell if he was chuckling or merely breathing heavily due to the slight ringing in your ears.

It had been so sudden that you weren’t expecting it, nor were you prepared for it. With your mind being the jumbled mess that it was, there was no longer any discernment between pleasure and pain. Incoherent mumbles and loud squeaks tumbled from your mouth as Cu let go of your neck and hips, only to wrap both of his arms around your torso for better leverage.

As he pursued his own orgasm, Cu was everything but gentle with you, using your body as if you were a mere sex toy. Heavy pants and low grunts filled your ears as your head drooped, feeling far too exhausted to do much of anything besides let him use you.

From the sheer force that he was exerting to pound into you, it was evident that there would be bruises for you to find later... Even then, that was an afterthought as you came once again, as overstimulated as you were. Your Berserker followed soon after, flooding your belly with his hot seed until you felt entirely too full.

He held onto you throughout the entire ordeal, leaning over you to whisper in your ear. You had already passed out, however, so you didn’t catch what he said. Once he realized that you were unresponsive, Cu chuckled and released his hold on you, allowing you to slide off of his cock. A large grin overtook his face as he watched his cum pour from your stretched hole.

“Heh, told you so.”

* * *

An undetermined amount of time had passed before you regained consciousness, waking up to find Cu’s cloak wrapped around you whilst you rested against a tree. It was getting fairly dark now, but you could see the stars clearly. A small yawn slipped past your parted lips as you looked to the sky, wondering when day would be.

“You were out for a while. Did the transfer wear you out _that_ much?” Feeling just a little groggy and annoyed, you turned toward the voice teasing you with a pout on your face.

Cu was resting against a tree not too far from you with his arms folded and placed atop his knees. You weren’t sure if he had been watching your surroundings, or just you.

“You overdid it on purpose, don’t try to make it sound like I’m just unbelievably weak!” As he laughed, you pouted even more, retreating further into the warmth of his cloak.

Even with it wrapped around your upper half, your legs were still exposed, therefore cold. You could feel your body beginning to shake as you shivered, teeth clicking together noisily. It must have gotten to the point of blatant annoyance, if Cu’s exasperated sigh was anything to go by.

“Come over here. Your chattering teeth are bothersome. I won't be able to rest.” He beckoned you over, which caused your eyebrows to raise in shock. You hadn’t thought Cu Chulainn Alter would be one for cuddling.

Once you were close enough to feel the heat radiating from his body, he reached out and wrapped the cloak around the two of you, bringing you closer until you were all but pressed into his side. With a contented sigh, you closed your eyes and leaned your head on his shoulder.

“I didn’t know you were such a softie, Cu~.” You had expected him to just shove you away immediately, but he didn’t. If anything, he had unconsciously snuggled up to you in return.

 _”Tch,_ be quiet or I’ll move and take my cloak with me.”

**Author's Note:**

> My Tumblr: hime-bee
> 
> My Twitter: himebeee
> 
> Feedback, comments and kudos are, as always, much appreciated!  
> ♡(●´ω｀●)
> 
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